1. College of Geosciences and Surveying Engineering,China University of Mining and Technology (Beijing),Beijing　 100083,China; 2. State Key Laboratory of Coal and CBM Co-mining,Shanxi Jincheng Anthracite Mining Group Company,Ltd. ,Jincheng　 048000,China

采用沁水盆地3个典型煤矿中、高煤阶煤样,开展了实验室煤样流速敏感性实验,分析了不同流速条件下煤样渗透率的变化规律,建立了煤储层渗透性与流速之间的关系和模型,揭示了中、高煤阶煤储层流速敏感性的控制机理。研究结果表明,煤样渗透率随流速发生变化,且存在一个临界流速。在临界流速之前随着注入流量(或流速)的增加煤样渗透率增加,当流速超过临界流速后,煤样的渗透率随着流体流速的增加反而减少。煤储层流速敏感性主要受控于煤储层物性和煤中速敏矿物。随着煤储层孔隙度、渗透率和流体流量的增高,煤储层速敏损害率按对数函数关系增高。实验煤样黏土矿物占矿物质含量为66.63%~99.89%,主要以高岭石、伊利石为主,存在潜在的速敏伤害,速敏实验结果表明,本区实验煤样存在不同程度的速敏损害,煤样速敏损害程度由弱至中等偏强,临界流速低。随着煤中黏土矿物含量的增加,煤储层速敏损害率也增高。在煤层气井排采过程中,寺河煤矿和西山煤矿煤层气井排采降速应为赵庄煤矿的6倍左右。

By using medium and high rank coal samples from three typical coal mines in Qinshui Basin,an experimen-tal study on flow rate sensitivity has been carried out. The permeability variation under different flow conditions is ana-lyzed and the relationship models between coal reservoir permeability and flow rate are established. Furthermore,the control mechanisms of flow rate sensitivity about medium and high-rank coals are revealed. It is shown that the coal sample permeability varies with the flow rate,and there is a critical flow velocity. Before the critical flow rate,with the increase of injection flow rate (or velocity),the permeability of coal sample increases. When the velocity exceeds the critical value,coal permeability will decrease with the rise of injection flow rate. The flow rate sensitivity is mainly con-trolled by coal physical properties and flow rate sensitive minerals. With the increase of porosity,permeability and fluid flow rate of coal reservoir,the flow sensitive damage rate of coal reservoir increases as logarithmic function. The clay minerals in the experimental coal samples accounts for 66. 63% -99. 89% ,and are mainly kaolinite and illite. So it in-dicates these coals exist potential flow rate sensitive damage. The results of flow rate sensitive experiment show that the coal samples in this area have different degrees of flow rate sensitive damage,and the flow rate sensitive damage degree of coal sample is from weak to moderate strong,the critical velocity is lower. With the increase of clay mineral content in coal,the flow sensitive damage rate of coal reservoir is also increased. In the process of CBM well drainage,pressure drop rate of Sihe and Xishan Coal Mine should be about six times of that of Zhaozhuang Coal Mine.

国家自然科学基金资助项目(41372163)；国家科技重大专项资助项目(2016ZX05067001-006)；山西省煤层气联合研究基金资助项目(2014012001)；

MENG Zhaoping,HOU Anqi,ZHANG Peng,et al. Experimental study on flow rate sensitivity of coal in typical coal mining area of Qinshui Basin and its control mechanism[J]. Journal of China Coal Society,2017,42(10):2649-2656.